Structure and magnetic properties of the $S=3/2$ zigzag spin chain antiferromagnet BaCoTe$_2$O$_7$

TL;DR

This study investigates the structure and magnetic properties of BaCoTe$_2$O$_7$, revealing a canted zigzag spin chain with antiferromagnetic order, magnetic frustration, and potential for polarization change via exchange striction.

Contribution

It provides the first detailed structural and magnetic characterization of BaCoTe$_2$O$_7$, highlighting its canted zigzag spin chain and multiferroic potential.

Findings

BaCoTe$_2$O$_7$ has a noncentrosymmetric structure with a canted $$ spin order.

The compound exhibits an antiferromagnetic transition at 6.2 K and strong magnetic frustration.

An indirect band gap of 2.68 eV is identified, suggesting potential multiferroic behavior.

Abstract

We report an investigation on structure and magnetic properties of the $S=3/2$ zigzag spin chain compound BaCoTe$_2$O$_7$. Neutron diffraction measurements reveal BaCoTe$_2$O$_7$ crystallizes in the noncentrosymmetric space group $Ama2$ with a canted $\uparrow\uparrow\downarrow\downarrow$ spin structure along the quasi-one-dimensional zigzag chain and a moment size of $1.89(2)\mu_B$ at 2 K. Magnetic susceptibility and specific heat measurements yield an antiferromagnetic phase transition at $T_N=6.2$ K. A negative Curie-Weiss temperature $\Theta_{CW}=-74.7(2)$ K and an empirical frustration parameter of $f=|\Theta_\text{CW}|/T_\text{N}\approx12$ is obtained from fitting the magnetic susceptibility, indicating antiferromagnetic interactions and strong magnetic frustration. By employing ultraviolet-visible absorption spectroscopy and first principles calculations, an indirect band gap of 2.68(2) eV is determined. We propose that the canted zigzag spin chain of BaCoTe$_2$O$_7$ may produce a change of the polarization via exchange striction mechanism.